Oven-thermometer



(No Model.) 8 Q 2 Sheets-Sheet 1 J. STIDHAM.

OVEN THERMOMETER.

. Nd. 384,876. Patented June 19, 1888.

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(No Model.)

J. STIDHAM.

OVEN THERMOMBTBR.

PatentdJ'un 19,]1888.

% WITNESSES.

N. PETER$, Phwn-Lhhox p' n Washington, M;

UNITED STATES PATENT OFFI E.

JOHN-STIDHAM, OF ROCHESTER, PENNSYLVANIA.

OVEN-THERMOMETER.

SPEQIPICATION forming part of Letters Patent No. 384,87 6, dated June 19, 1888. Application filed Dccembrr 15, 1887. Serial No. 257,930. (No model.)

To all whom it may concern.-

Be it known that I, JOHN STIDHAM, a citizen of the United States of America, residing at Bochester,in the county of Beaver and State of Pennsylvania, have invented certain new and useful Improvements in Heat-Indicators for Ovens; and I do hereby declare the following to bea full, clear, and exact description of the invention, such as will enable, others skilled in the art to which it appertains to make and use the same, reference being had to the acconr panying drawings, and to letters or figures of reference marked thereon,which form a part of this specification.

My invention relates to certain new and useful improvements in heat-indicators for ovens; and it consists in the novel construction and arrangement of the parts, which will be more fully hereinafter described, and particularly pointed out in the claims.

The object of my invention is to provide a novel device for attachment to ovendoors for indicating, bya suitable dial on the outside of the door, the heat of the oven, the said dial having a hand revolved and controlled in its indication by the expansion and contraction of two metallic bars operating suitable mechanism. I attain this object by the construction illustrated in the accompanying drawings, wherein like letters of reference indicate similar parts in the several views, and in which Figure 1 is a rear elevation of an oven-door, showing the rear side of my improved construction. Fig. 2 is a front elevation of an oven-door, showing the dial-plate and'indicator. Fig. 3 is an elevation of a portion of my improved construction. Fig. 4 is a transverse vertical section. Fig. 5 is a perspectwe View of a part of the mechanism, showing the connection of the bell-crank and gravity 1evers with the arbor, the supportingframe being partially broken away.

A indicates an oven-door of any preferred form of construction, which has a metallic disk, B, secured thereto. The said disk B is provided with a central aperture, through which an arbor, b, passes, on'the outer or front end of which a hand, I), is mounted, which operates in connection with a dial-plate pro- Vided with degree-marks. The said plate B is also formed with suitable blocks, b each of which is provided with screw-threaded apertures, and upon these space-blocks b a plate, B, is secured. bcllcrank lever, O, is mounted, which is provided at its upper end with apertures engaged by a chain, C, which passes around the cen- Between the plates B and Ba situated and supported within an angle-plate secured to the back of the plate B. The attachment of the bars to the oven-door allows them to have a vertical movement at this point. The bevels on the innerends thereof are at an angle to each other, as shown in dotted lines, Fig. 1.

WVhen the heat of the oven acts upon the sectional bar, the natural tendency will be to expand the same, and said expansion being restrained will cause the central portion or opposing ends of the said bars to rise upward,

when the wrist-pin a will be drawn upward with the section with which it engages and throw the bell-crank lever away from the arbor b and cause the chain to revolve the same by engagement therewith, as hereinbefore described. The revolution of said arbor will of necessity revolve the hand on the dial and indicate the degree of heat of the oven. The more intense the heat of the oven the greater will be the expansion of the bars E, and consequently the hand on the dial will continue to revolve around the face of the dial as the heat increases. As soon, however, as the oven cools, the hand will revolve backward over the face of the dial, and when it reaches such a point that the gravity-lever D will act upon the chain 0 the said lever will dropand bring the hand on the dial at the zero-point.

It will be understood that in the operation of the bell'crank lever O in its movement away from the arbor an upward force will be exerted upon the chain 0, which will raise the gravity-lever D.

Having thus described my invcnlion,what I claim as new is- 1. The combination, with the ovendoor, of the plates B and B, central arbor, b, bell-crank lever 0, having wrist-pin 0 on its lower end, chains 0 and O, gravity-lever D, and the bars E, all arranged and operating substantially as described. a

2. The combinatiomwith the oven-door,ofthe plates B and B, the central arbor, b, carrying a hand on its outer end adapted to engage with the dial-plate, the bellcrank lever 0, having the upper end of its longer arm provided with a series of apertures, the chain 0, connected at its upper end to said arm of the bell-crank 

